The present invention relates to a powdered product suitable for the preparation of emulsions, and more specifically, to a powdered product prepared by dispersing (a) an oil; (b) a solution of a drug or nutriment in oil; or (c) an emulsion of an aqueous solution of a drug or nutriment in oil, in an aqueous solution containing a surface layer former and, where appropriate a drug or nutriment, and then spry-drying the resulting dispersion.
Heretofore, there have been known water-in-oil emulsion products prepared by emulsifying an aqueous solution of a water-soluble drug in oil. Also, there have been reports of water-in-oil-in-water emulsion products obtained by further emulsifying the water-in-oil emulsion in water.
Such products have been frequently used in the clinical administration of a drug or nutriment together with a suitable oil. For example, where an emulsion of an aqueous solution of an anti-cancer substance such as 5-fluorouracil, bleomycin and mitomycin C, and an oil is administered, the drug has a lymphatic directivity due to the property of the co-existing oil. Therefore, the drug selectively reaches the lymph nodes at a high concentration. Such characteristic is of great importance in administering an anti-cancer substance for the treatment of metastases of cancer to lymph nodes. In addition, where an analgesic, an antibiotic or the like is incorporated into fine particles of an oil and such is administered by injection, where the size of the particle of oil is larger than a predetermined certain size, the particle is maintained in the capillary vessels. In this case, the active ingredient, i.e. the drug, gradually permeates into the surrounding tissues. Therefore, the concentration of the drug in the specific tissue can be maintained at a high level for a long period of time. This apparently results in an enhanced durability of the effect of the drug. Moreover, it can easily be understood that such method would be effective to administer an oil together with nutriments such as amino acids and glucose to a patient who has undergone a surgical operation. In addition, it is possible in such manner to administer an oil itself, as a nutriment, in the form of an emulsion.
From the foregoing, it will be understood that a double emulsion of a water-in-oil emulsion in water or an oil-in-water emulsion is very useful. However, the stability of the emulsion per se or that of drugs or nutriments is not at all satisfactory. More specifically, when an emulsion once prepared is preserved for a long period of time, the emulsion structure is destroyed thus separating into oil and water. Moreover, the drug or nutriment which is an active ingredient is not necessarily stable.